us-county-airdata-trends

U.S. county-level 5-year AirData emission trends, derived from EPA AirData annual AQI summaries 2020-2024.

Sensitivity-gated 5-year change classification for 994 US counties, with explicit display-hold flags for counties below the facility-count floor (368 counties) and the 4 petrochemical-corridor counties that surface a methodology-review notice instead of a trend value.

Produced by ZipCheckup Trend Layers v1. Display methodology underwent a 4-agent legal pre-build review (FTC compliance + defamation/stigmatization + statistical methodology + feeds feasibility) — see methodology page.

Install

npm install us-county-airdata-trends

Quick start

const airdata = require('us-county-airdata-trends');

// Look up a single county
const la = airdata.getCounty('06037');
// {
//   county_fips: '06037',
//   county_name: 'Los Angeles',
//   state: 'CA',
//   airdata_change_class: 'stable',
//   airdata_pct_change: -5.9,
//   cycles_used: 5,
//   facility_count: 331,
//   sensitivity_robust: null,
//   skip_reason: null,
//   source_attribution: 'EPA AirData annual AQI summaries 2020-2024',
//   petrochemical_corridor: false,
//   aqi_latest_year: 2024
// }

// All counties for a state
const texas = airdata.filterCounties({ state: 'TX' });

// Counties classified as decreasing (and display-eligible)
const decreasing = airdata.filterCounties({ changeClass: 'decrease', excludeSkipped: true });

// Display-eligible vs display-held — for methodology dashboards
const eligible = airdata.getDisplayEligibleCounties();
const held = airdata.getDisplayHeldCounties();

// Coverage metadata
console.log(airdata.meta);
// { generated: '2026-05-25', totalCounties: 994, coverage: { change_class_decrease: 67, ... }, ... }

Field schema

| Field | Type | Description | |-------|------|-------------| | county_fips | string | 5-digit US county FIPS code | | county_name | string | null | County name without "County" suffix | | state | string | null | 2-letter state abbreviation | | airdata_change_class | "decrease" \| "increase" \| "stable" \| "insufficient_data" | null | Sensitivity-gated 5-year class | | airdata_pct_change | number | null | Signed percent change between earliest and latest cycle | | cycles_used | integer | null | Number of reporting cycles (target 5, minimum 3) | | facility_count | integer | null | Distinct facilities in latest cycle (display gate ≥5) | | sensitivity_robust | boolean | null | True if direction stable when top-1 facility excluded | | skip_reason | string | null | "facility_count_below_threshold" | "petrochemical_corridor" | "cycles_below_threshold" | null | | source_attribution | string | Required attribution string for any public render | | petrochemical_corridor | boolean | True for 4 corridor counties (Harris TX, Calcasieu LA, Iberville LA, Kanawha WV) | | aqi_latest_year | integer | null | Latest reporting year included in window |

Full machine-readable schema: data/metadata.json.

Coverage (snapshot)

| Class | Counties | |-------|---------:| | decrease | 67 | | increase | 176 | | stable | 376 | | insufficient_data (display held) | 375 | | Total | 994 |

Of which display-held:

• facility_count_below_threshold: 368
• petrochemical_corridor: 4

Use cases

• Journalism / civic data: county-level air-quality trend reference for explanatory reporting. Use getDisplayEligibleCounties() to filter out underpowered counties.
• Research / academia: sensitivity-gated trend classification suitable for downstream regression as a county-level feature; raw airdata_pct_change available for the 994 counties with sufficient cycle coverage.
• Embed / widget: county trend lookup for embeddable badges (see also API endpoint).

Methodology

Source: EPA AirData annual AQI summaries (annual_aqi_by_county_{YEAR}.zip), years 2020-2024, retrieved via https://aqs.epa.gov/aqsweb/airdata/download_files.html.

Pipeline:

1. Aggregate facility-reported emissions to county rollups per year.
2. Compute percent change between earliest and latest cycle.
3. Apply sensitivity gates:
   • ≥3 reporting cycles in window
   • ≥5 reporting facilities in latest cycle
   • Top-1-exclude robustness: direction unchanged when largest facility excluded
4. Bucket as decrease / increase / stable (|pct_change| < 10%) / insufficient_data.
5. Hold display for 4 petrochemical-corridor counties pending methodology review (Harris TX 48201, Calcasieu LA 22019, Iberville LA 22047, Kanawha WV 54039) — see petrochemical_corridor boolean.

See full methodology: zipcheckup.com/methodology/airdata-trend/.

Caveats

• This is facility-reported emissions data, not ambient air quality. The trend reflects what facilities reported to EPA — not what residents breathe.
• AirData updates may reflect reporting methodology changes between cycles. Disclose this in any user-facing render.
• 4 petrochemical-corridor counties surface as skip_reason: "petrochemical_corridor" with a methodology-review notice; do not silently treat them as insufficient_data.
• This package is updated periodically. The meta.generated field surfaces the build date — check it before using for time-sensitive analysis.

License

CC BY 4.0. Free to use with attribution.

Citation

Akulov, A. (2026). U.S. County AirData 5-Year Emission Trends [Data set].
ZipCheckup. https://doi.org/10.5281/zenodo.20382474

Or BibTeX:

@dataset{zipcheckup_us_county_airdata_trends,
  author    = {Akulov, Artem},
  title     = {U.S. County AirData 5-Year Emission Trends},
  year      = {2026},
  publisher = {ZipCheckup},
  doi       = {10.5281/zenodo.20382474},
  url       = {https://doi.org/10.5281/zenodo.20382474}
}

Related

• us-water-quality-data — ZIP-level water quality dataset (sibling package).
• us-housing-risk-data — Housing risk and home values (sibling package).
• ZipCheckup Public API — REST API including /v1/county/{fips}/airdata-trend/.

Source repository

github.com/artakulov/waterbyzipcode (this package lives under packages/us-county-airdata-trends/).